I read somewhere that I can use another Arduino as a programmer (have a spare Uno lying around), but how do I go about doing the whole thing?

If you are going to use a programmer regularly, just buy a USBasp off ebay for $5 or so. The "Uno as a programmer" is a good party trick, but a bit Rube Goldberg-ish for regular use. The USBasp will also have useful features like a slow clock generator.

The Arduino language & IDE has a bunch of annoying bugs and I'd like to just code it in plain old C. I have some experience with PIC mcus, but they're just rubbish :d

Lots of people program Arduinos without using the Arduino IDE. I myself use Emacs + makefiles, others use things like Eclipse + one of the plugins for Arduino. There are also several projects current where people are having their own crack at writing a better IDE. The thing is, it's the gnu compiler + avrdude sitting under the IDE that's really doing all the work -- the IDE just provides a simple editor and a certain amount of preprocessing of your "sketch" code into something that (hopefully) will be acceptable to the gcc compiler. What the IDE preprocessor really does isn't really that much (and it doesn't do it very well anyway, IMHO), so it's no great loss to work without it. Many (like me) see it a definite advantage, in fact.

You don't need to remove the bootloader in order to upload Arduino-less code.

Wait what?

The bootloader is just a piece of software that is loaded in the AVR that allowsa tool (avrdude in this case) to upload code to the AVR. The bootloader itselfis totally independent of anything Arduino.

As shipped the AVR fuses are set to create two sections in the FLASH. Bootloader and application.The "Arduino" bootloader is small piece of code in the AVR that uses the serial port to update the flashwith the user application (code/program/sketch).The bootloader runs at reset/powerup if there is no attempt to upload anything, the bootloaderwill start the application code.The application code can be written using any toolset you prefer. The Arduino tools are just one option.

avrdude is a tool that is used upload code into the flash.avrdude can be used with an ISP programmer to upload code to the flashavrdude can also use other mechanisms like a serial port that talks to a serial based programmer or to a bootloader.The Arduino IDE uses avrdude to talk over a serial port to a pre-installed bootloader in the AVR chip.The newer IDE can also use an ISP progammer to upload code. When an ISP programmer is used,a bootloader is not used so the flash space used by the bootloader code frees up and can be usedby the application code.

If you don't want to use a bootloader, you will need some sort of ISP programmer.Like Pico, I recommend getting a USBasp programmer off ebay.I like the USBasp kk multicopter programmers (about $5-$10 USD) because they come with a 6 pin ISPcable instead of 10 pin so no adapter is needed.

Coding..., out of curiosity why would you resort to using an Uno when you have a pololu programmer?Teensy I understand as it should be faster because of the native USB support, but why use Uno?

Upload performance from fastest to slowest...

• Uno with a 250K baud bootloader

• Pololu (very close to the same speed as above)

• Teensy running TinyISP

• Uno running TinyISP

• Teensy running ArduinoISP

• Uno running ArduinoISP (very slow)

The first two are very close to the programming time listed in the Atmel datasheet and are essentially the fastest possible method using SPI. (Again, I highly recommend the Pololu AVR Programmer. It was worth the $20 I paid for it (now just $10).)

TinyISP on either hardware is not as fast by a noticeable amount but is still fast enough to fall within the "two second" rule1.

ArduinoISP is just abysmal.

I use the Uno or Teensy because of the amenities that I've added to the Arduino ISP sketch (TinyISP is available here). It makes a "good enough" programmer with some very basic debugging tools.

I like the Teensy because, inserted in a breadboard, it makes a very nice "project board". Breadboard + programmer + basic debugging for ~$30. What's not to like?

I like the Uno because it's easier to move from one project to another. Getting the Teensy out of a breadboard is a little annoying.

1 Humans perceive a computer response within two seconds to be reasonable. At five seconds, humans tend to get impatient and annoyed. At ten seconds, they tend to get angry. Past that, the monitor gets a fist, a boot, or a bullet.

I'm working on a project where I have to upload via ISP (not bootloader) and I am uploading a sketch of 9308 bytes (program memory) or 26208 bytes (hex file size) in 11 seconds, using the Arduino via SD card system I devised.

http://www.gammon.com.au/forum/?id=11638

I don't feel particularly annoyed at waiting that long. That time includes reading the file from SD and checking its integrity, uploading and then verifying the upload. There is an additional overhead of a few seconds to move the SD card from the Mac to the card reader.

Please post technical questions on the forum, not by personal message. Thanks!